The MK Airlines Boeing 747 crash site is
seen from the air on Tuesday near the
Halifax International Airport.

The end of the runway where an MK
Airlines Boeing 747 hit before crashing
is seen from the air on Tuesday.

The flight data recorder, still being
investigated in Ottawa, lies at the
crash site earlier this week.

Investigators sift through debris at the
crash site of an MK Airlines Boeing 747.

The MK Airlines 747 crash site near the
Halifax International Airport is seen
from the air Tuesday. A cockpit voice
recorder found at the scene was ruined
in the fiery crash, but investigators
hope to glean some information from the
data flight recorder.

Searchers comb through wreckage at the
crash site at the Halifax International
Airport.

It may be days before investigators are
able to begin to remove the larger
sections of wreckage.

No one will ever know what the crew of an MK
Airlines Boeing 747 said to each other before
last week's fatal crash at the Halifax
International Airport.

"We had a significant milestone (Monday) when
we recovered the cockpit (voice) recorder, that
was the good news," Bill Fowler of the
Transportation Safety Board told a Tuesday news
conference.

"The not-so-good news is that the recorder
was damaged such that there was no retrievable
data."

Flight 1602, heading for Spain, careened off
the end of Runway 24 and burst into flames
Thursday around 4 a.m., killing all seven
aboard.

Investigators have a tape of the conservation
between the crew and air controllers before the
crash, but Mr. Fowler said it likely won't be
released.

He said he was unaware of any indication on
the recording of a problem on the
Ghanaian-registered plane.

Investigators also have the damaged flight
data recorder that was retrieved Sunday. It has
been repaired and specialists have determined
that it recorded 107 pieces of data related to
various onboard systems, Mr. Fowler said.

That information still has to be analysed by
the safety board's engineering office in Ottawa,
which could take up to a couple of weeks.

"If we do get it (the data), it will
certainly answer several questions and provide
us with some significant information," Mr.
Fowler said.

Investigators are also looking at the plane's
maintenance and performance. They still don't
know why its four engines were recently replaced
in Indonesia, but they are especially interested
in how the new engines were working at the time
of the crash.

They want to know the speed at which they
were turning, the amount of thrust produced, the
exhaust gas temperature, and how fast the plane
was travelling, Mr. Fowler said.

If information on the flight data recorder is
unusable, he said investigators are ready to use
"traditional methods," including a physical
examination of the engines.

"It is much less refined than if you had a
recorder."

The plane also had a "quick access recorder"
that has not been found, said Mr. Fowler, adding
the device is unprotected and would have been at
the centre of destruction.

The investigators, including the Canadian
safety board, the RCMP, Federal Aviation
Administration and National Transportation
Safety Board, as well as aviation authorities
from Britain and Ghana, are also probing the
jet's weight. That's difficult to determine
based on physical evidence at the crash site,
Mr. Fowler said, but they've started tracing the
cargo back to its source to see how much the
plane was carrying.

Officials in Hartford, Conn., were trying to
get specific cargo information from Bradley
International Airport where the plane loaded up
before heading to Halifax.

The day of the crash, MK Airlines official
Steve Anderson said the plane was almost half
full of John Deere lawn tractors and "general
freight, which is everything from computers to
anything you can imagine."

After it arrived in Halifax, it was also
loaded with 53,405 kilograms of silver hake and
lobster destined for Spain.

Mr. Anderson has said the cargo weighed 103
tonnes and that the plane could carry 110
tonnes.

Investigators have ruled out nothing,
including speculation the cargo may have shifted
during takeoff.

The flight data recorder might help determine
whether that happened, possibly through a change
in acceleration, Mr. Fowler said.

Investigators will also look at the wreckage
and inspect the loading and cargo mechanics.

As well, they have studied a videotape of the
aircraft turning on to the runway, Mr. Fowler
said.

"I can't tell you exactly where the aircraft
turned but we're confident that almost all the
runway was utilized - they were very close to
the end."

Investigators were taking daylight photos at
the exact location of the video camera, which
"will tell us quite accurately" where the plane
started its acceleration.

It may be days before investigators begin
removing larger pieces of wreckage from the site
because roads need to be built to get heavy
equipment in, Mr. Fowler said.

From a helicopter flying 150 metres above the
crash site Tuesday, backhoes could be seen
digging and spreading gravel for two roads
running from the Old Guysborough Road to the
doomed plane's fuselage in woods across from the
airport.

The path of destruction began past the end of
Runway 24, where the aircraft tried to take off.

Investigators say the tail of the jet bounced
twice off the tarmac near the end of the runway
and separated from the plane when it hit a mound
of earth 300 metres beyond the end of the
runway.

From the helicopter there were no gouges
visible in the pavement, but two tire marks in
the brown grass led to a line of orange posts,
part of the airport's navigational system.

Two of the posts were on the ground, followed
by the tail of the plane with the airline's
logo, a red M and a blue K, smaller pieces of
debris and another part of the tail.

The debris field ended before the trees at
the airport fence that lines Old Guysborough
Road. There was nothing visible on the pavement,
except for RCMP cruisers blocking access to
motorists.

Green military tents, trailers, portable
toilets, cars, trucks and vans - the on-site
base for investigators - lined a dirt road
leading from inside the airport fence to the
paved road.

On the opposite side of Old Guysborough Road,
the rest of the wreckage stretched out in almost
a straight line from the end of the runway.

The charred fuselage was surrounded by
scorched trees and bits of metal like burned
shreds of paper scattered about.

Beyond the fuselage, amidst the ash-like
debris, lay three pieces of metal, two yellow
and one bright green, the colours of the famous
John Deere tractor company.

Making Sure the Recorders
Survive
Things have come a long way
since 1958 when it was the
state-of-the-art in
crash-survivability that had the
major influence on the level of
the minimum requirements for
crash-survivability. Today the
minimum standards are set
according to the conditions that
a flight recorder is likely to
meet in a crash.
These days to become certified
for use flight recorders must
pass a collection of extremely
arduous tests. These include:

Fire.

This is two-fold, the flight
recorder casings must protect
the recording medium from
1100degC (the temperature at
which aviation fuel burns) for
thirty minutes (simulating the
initial fuel fire after a
crash). It must then be able to
protect the recording medium
from a temperature of 260degC
for ten hours (this simulates a
long baggage-fuelled fire).
Common heat-insulation materials
used include polymers, wax and
gelled which - all offer good
protection from high
temperatures.

Water
protection and Deep Sea Water
Pressure Resistance.

The casing must protect the
recording medium for thirty days
underwater at a pressure
equivalent to being submerged at
20,000ft below the ocean
surface.

Static
Crush Test.

The recorder must withstand a
5,000-pound pressure applied
against all six axis points.

Penetration Resistance.

The recorder must withstand a
500lb force being dropped on it
from 10 feet up, the point of
contact being a one-quarter inch
diameter hardened steel spike.

Impact
Test .

In this test the recorder is
fired from an air cannon into an
aluminium wall. This simulates
the required, 3400g deceleration
in 6.5 milliseconds (which is
equivalent to going from 350 mph
to zero in 16 inches).

Fluid
Immersion Test .

To check that the recorder will
not be eroded by any of the
fluids that are most commonly
carried by planes, the recorder
must survive emersion for 48
hours in each of the following:
hydraulic fluid
lubricating oil
aviation fuel
fire extinguishing agents
and toilet flushing fluid .